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Local-environment dependence of stacking fault energies in concentrated solid-solution alloys

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npj Computational Materials 2019年第1期5卷 1032-1038页

作者： Shijun Zhao yuri osetsky G.Malcolm Stocks Yanwen Zhang Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Department of Mechanical Engineering City University of Hong KongHong KongChina Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA

Concentrated solid-solution alloys(CSAs)based on 3d transition metals have demonstrated extraordinary mechanical properties and radiation resistance associated with their low stacking fault energies(SFEs).Owing to the intrinsic disorder,SFEs in CSAs exhibit distributions depending on local atomic configurations.In this work,the distribution of SFEs in equiatomic CSAs of NiCo,NiFe,and NiCoCr are investigated based on empirical potential and first-principles calculations.We show that the calculated distribution of SFEs in chemically disordered CSAs depends on the stacking fault area using empirical potential calculations.Based on electronic structure calculations,we find that local variations of SFEs in CSAs correlate with the charge density redistribution in the stacking fault region.We further propose a bond breaking and forming model to understand and predict the SFEs in CSAs based on the local structure alone.It is shown that the perturbation induced by a stacking fault is localized in the first-nearest planes for NiCo,but extends up to the third nearest planes for NiFe and NiCoCr because of partially filled d electrons in Fe and Cr.

关键词： alloys fault stacking

Tunable chemical complexity to control atomic diffusion in alloys

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npj Computational Materials 2020年第1期6卷 1360-1367页

作者： yuri osetsky Alexander V.Barashev Laurent K.Béland Zhongwen Yao Keyvan Ferasat Yanwen Zhang Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Department of Nuclear Engineering and Radiological Sciences University of MichiganAnn ArborMI 48109USA Department of Mechanical and Materials Engineering Queen’s UniversityKingstonON K7L 3N6Canada Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA

In this paper we report a new fundamental understanding of chemically-biased diffusion in Ni–Fe random alloys that is tuned/controlled by the intrinsic quantifiable chemical complexity.Development of radiation-tolerant alloys has been a long-standing challenge.Here we show how intrinsic chemical complexity can be utilized to guide the atomic diffusion and suppress radiation damage.The influence of chemical complexity is shown by the example of interstitial atom(IA)diffusion that is the most important defect in radiation effects.We useμs-scale molecular dynamics to reveal sluggish diffusion and percolation of IAs in concentrated Ni–Fe alloys.We develop a mean field diffusion model to take into account the effect of migrating defect energy properties on diffusion percolation,which is verified by a new kinetic Monte Carlo approach addressing detailed processes.We demonstrate that the local variations in the ground state energy of IA configurations in alloys,reflecting the chemical difference between alloying components,drives the percolation effects for atomic diffusion.Percolation,chemically-biased and sluggish diffusion are phenomena that are directly related to the chemical complexity intrinsically to multicomponent alloys.

关键词： alloys alloying diffusion

Atomic-scale mechanisms of void strengthening in tungsten

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Tungsten 2021年第1期3卷 65-71页

作者： yuri N.osetsky Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA

Neutron and heavy-ion irradiation of tungsten produces nanometer-size vacancy voids,gas-filled bubbles and dislocation loops.These defect features can a ect mechanical properties and the impact can be quite significant because of their high density.Understanding the basic mechanisms of mechanical properties degradation is necessary for predicting radiation e ects.Predictions can be made using discrete dislocation dynamics or/and finite element approaches which,however,need local interaction mechanisms as inputs.Such knowledge can be provided only by atomic-scale modeling.This paper reports the results of an extensive atomic-scale modeling study of the interactions between moving edge dislocations and voids in tungsten.The main focus is on the e ects of the void size and ambient temperature.Critical resolved shear stress was calculated for voids up to 9 nm in diameter.Atomistic results are compared with the theoretical approach and with those obtained earlier for voids in body centered cubic(bcc)iron.An important role of the void surface has been revealed.

关键词： Tungsten Neutron irradiation Voids Radiation-induced hardening Dislocations Dispersed barrier hardening

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Atomistic material behavior at extreme pressures

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npj Computational Materials 2016年第1期2卷 93-96页

作者： Laurent Karim Béland yuri N osetsky Roger E Stoller Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTNUSA

Computer simulations are routinely performed to model the response of materials to extreme environments,such as neutron(or ion)irradiation.The latter involves high-energy collisions from which a recoiling atom creates a so-called atomic displacement cascade.These cascades involve coordinated motion of atoms in the form of supersonic shockwaves.These shockwaves are characterized by local atomic pressures 415 GPa and interatomic distances o2Å.Similar pressures and interatomic distances are observed in other extreme environment,including short-pulse laser ablation,high-impact ballistic collisions and diamond anvil cells.Displacement cascade simulations using four different force fields,with initial kinetic energies ranging from 1 to 40 keV,show that there is a direct relationship between these high-pressure states and stable defect production.An important shortcoming in the modeling of interatomic interactions at these short distances,which in turn determines final defect production,is brought to light.

关键词： extreme defect latter

High-Q resonant terahertz metasurfaces

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Opto-Electronic Advances 2024年第4期7卷 1-3页

作者： Manukumara Manjappa yuri Kivshar Department of Instrumentation and Applied Physics Indian Institute of ScienceBengaluru 560012India Nonlinear Physics Center Australian National UniversityCanberra ACT 2601Australia

In photonics,the quest for high-quality(high Q)reson-ances driven by the physics of bound states in the con-tinuum(BIC)1,2 has motivated researchers to explore in-novative avenues for realizing groundbreaking applica-tions in lasing3,sensing4 and nonlinear photonics5.A conventional strategy to harness the properties of BICs involves breaking the symmetry of resonators in a uni-form lattice,allowing uncoupled modes to interact with free space that opens a leaky channel in the form of so-called(quasi)qBIC6 modes.It is imperative that to un-lock the full potential of photonic BICs,the approach should involve not only a fundamental understanding of their underlying physics but also innovative engineering strategies to tailor their properties for various applica-tions.

关键词： breaking resonant symmetry

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Neurogenic potential of NG2 in neurotrauma:a systematic review

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Neural Regeneration Research 2024年第12期19卷 2673-2683页

作者： yuri R.Rigo Radharani Benvenutti Luis V.Portela Nathan R.Strogulski Departamento de Bioquímica Instituto de Ciências Básicas da SaúdeUniversidade Federal do Rio Grande do Sul(UFRGS)Porto AlegreBrazil School of Pharmacy and Biomolecular Sciences RCSI University of Medicine and Health SciencesDublinIreland School of Biochemistry and Immunology Trinity Biomedical Sciences InstituteTrinity College DublinUniversity of DublinDublinIreland

Regenerative approaches towards neuronal loss following traumatic brain or spinal cord injury have long been considered a dogma in neuroscience and remain a cutting-edge area of research.This is reflected in a large disparity between the number of studies investigating primary and secondary injury as therapeutic to rgets in spinal co rd and traumatic brain injuries.Significant advances in biotechnology may have the potential to reshape the current state-of-the-art and bring focus to primary injury neurotrauma research.Recent studies using neural-glial factor/antigen 2(NG2)cells indicate that they may differentiate into neurons even in the developed brain.As these cells show great potential to play a regenerative role,studies have been conducted to test various manipulations in neurotrauma models aimed at eliciting a neurogenic response from them.In the present study,we systematically reviewed the experimental protocols and findings described in the scientific literature,which were peer-reviewed original research articles(1)describing preclinical experimental studies,(2)investigating NG2 cells,(3)associated with neurogenesis and neurotrauma,and(4)in vitro and/or in vivo,available in PubMed/MEDLINE,Web of Science or SCOPUS,from 1998 to 2022.Here,we have reviewed a total of 1504 papers,and summarized findings that ultimately suggest that NG2 cells possess an inducible neurogenic potential in animal models and in vitro.We also discriminate findings of NG2 neurogenesis promoted by different pharmacological and genetic approaches over functional and biochemical outcomes of traumatic brain injury and spinal co rd injury models,and provide mounting evidence for the potential benefits of manipulated NG2 cell ex vivo transplantation in primary injury treatment.These findings indicate the feasibility of NG2 cell neurogenesis strategies and add new players in the development of therapeutic alternatives for neurotrauma.

关键词： neural-glial antigen 2 neural-glial factor 2 neuron differentiation NG2 cell regeneration spinal cord injury(SCI) traumatic brain injury(TBI)

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Dynamic ultrasonography for optimizing treatment position in superior mesenteric artery syndrome:Two case reports and review of literature

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World Journal of Gastroenterology 2024年第5期30卷 499-508页

作者： Nobuaki Hasegawa Akihiko Oka Muyiwa Awoniyi yuri Yoshida Hiroshi Tobita Norihisa Ishimura Shunji Ishihara Department of Internal Medicine II Shimane University Faculty of MedicineIzumo 693-8501ShimaneJapan Department of Gastroenterology Hepatology and NutritionDigestive Disease and Surgery InstituteHepatology SectionCleveland ClinicClevelandOH 44195United States Clinical Laboratory Division Shimane University HospitalIzumo 693-8501ShimaneJapan Division of Hepatology Shimane University HospitalIzumo 693-8501Japan

BACKGROUND Superior mesenteric artery(SMA)syndrome is a rare cause of duodenal obstruction by extrinsic compression between the SMA and the aorta(SMA-Ao).Although the left lateral recumbent position is considered effective in the treatment of SMA syndrome,individual variations in the optimal patient position have been noted.In this report,we present two elderly cases of SMA syndrome that exhibited rapid recovery due to ultrasonographic dynamic evaluation of the optimal position for each patient.CASE SUMMARY Case 1:A 90-year-old man with nausea and vomiting.Following diagnosis of SMA syndrome by computed tomography(CT),ultrasonography(US)revealed the SMA-Ao distance in the supine position(4 mm),which slightly improved in the lateral position(5.7–7.0 mm)without the passage of duodenal contents.However,in the sitting position,the SMA-Ao distance was increased to 15 mm accompanied by improved content passage.Additionally,US indicated enhanced passage upon abdominal massage on the right side.By day 2,the patient could eat comfortably with the optimal position and massage.Case 2:An 87-year-old woman with vomiting.After the diagnosis of SMA syndrome and aspiration pneumonia by CT,dynamic US confirmed the optimal position(SMA-Ao distance was improved to 7 mm in forward-bent position,whereas it remained at 5 mm in the supine position).By day 7 when her pneumonia recovered,she could eat with the optimal position.CONCLUSION The optimal position for SMA syndrome varies among individuals.Dynamic US appears to be a valuable tool in improving patient outcomes.

关键词： Superior mesenteric artery syndrome Wilkie’s syndrome Cast syndrome Aorto-mesenteric compass syndrome Ultrasonography Case report

How the adoption of industry 4.0 technologies is related to participation in global and domestic value chains: Evidence from Russia

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International Journal of Innovation Studies 2024年第2期8卷 93-108页

作者： Anna A.Fedyunina Nikolay A.Gorodnyi yuri V.Simachev Centre for Industrial Policy Studies National Research University Higher School of EconomicMoscow11Pokrovsky BoulevardZip Code:101000Russia

This study explores the relationships among Industry 4.0 technologies, their application areas,and the involvement of Russian manufacturing firms in global and domestic value chains. Weapply logit and multinomial logit regressions using an original survey dataset of approximately1700 Russian manufacturing firms. We make a novel contribution to the literature by uncoveringan asymmetry in adopting Industry 4.0 technologies among Russian industrial firms in domesticvalue chains (DVCs) and global value chains (GVCs). This asymmetry has the potential to impedeGVC localization and DVC internationalization. Based on our results, software automation solu-tions are the only ones demonstrating statistical significance for firms participating simulta-neously in GVCs, DVCs, and both GVCs and DVCs. Companies in DVCs demonstrate a broaderutilization of Industry 4.0 technologies across various application areas. We also identify evidenceof reshoring in DVCs, indicating that Industry 4.0 adoption encourages firms to establish enduringrelationships with domestic suppliers. Highlighting that differences in technology adoption areinfluenced by external factors, including adherence to international standards and regulatoryprinciples, we propose policy implications for developing countries. Recommendations encom-pass reducing entry barriers to DVCs, improving procurement transparency, and promotingcompetition in the digital solutions market to empower firms for seamless GVC integration.

关键词： Industry 4.0 Global value chains Domestic value chains Forward linkages Backward linkages

Resonantly enhanced second-and third-harmonic generation in dielectric nonlinear metasurfaces

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Opto-Electronic Advances 2024年第5期7卷 8-23页

作者： Ji Tong Wang Pavel Tonkaev Kirill Koshelev Fangxing Lai Sergey Kruk Qinghai Song yuri Kivshar Nicolae C.Panoiu Department of Electronic and Electrical Engineering University College London Nonlinear Physics Center Research School of PhysicsAustralian National University Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsHarbin Institute of Technology Wuzhen Laboratory EGO Wuzhen Digital Economy Industrial Park

Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and sensing.Here,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical response.Exploiting the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the meta-atoms.Next,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is observed.To gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the meta-atoms.Our work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices.

关键词： all-dielectric metasurfaces bound state in the continuum guided mode resonance nonlinear optics second-harmonic generation third-harmonic generation